Incoming cell control method and device for mobile communication device

ABSTRACT

An incoming call control method and device for a mobile communication device, can respond to an incoming call swiftly, even in cases where there has been a failure in a response to an incoming call signal from a base station. In a mobile communication device which selects a control channel by scanning control channels for transmitting and receiving control signals to and from a base station, assumes a standby state awaiting an incoming call signal transmitted by a base station using the control channel thus selected, and establishes a communication channel with the base station by making incoming call response to an incoming call signal when an incoming call signal is received from a base station in the standby state. The mobile communication device returns to the standby state without carrying out scanning for a new control channel when the incoming call response to an incoming call signal from the base station has failed.

TECHNICAL FIELD

This invention relates to an incoming call control method and device ina mobile communication device for carrying out communication by radiobetween a base station and a mobile device, and more particularly, to anincoming call control method and device for a mobile communicationdevice which is improved in such a manner that it is capable ofresponding to incoming calls swiftly even in cases where it has failedto respond to an incoming call signal from the base station.

BACKGROUND ART

In general, mobile communication devices of this kind (hereinafter,simply called mobile devices) are constituted such that:

1) When the power supply is turned on, the mobile device scans controlchannels, and selects the control channel having the greatest fieldstrength as the control channel by which it is to transmit and receivecontrol signals to and from a base station (P-CH scan).

2) When a control channel has been selected, the mobile device receivescontrol data transmitted by the base station using the selected controlchannel so as to be ready for calling operation by the mobile device orreceiving an incoming call signal from the base station (standby state).

3) When the mobile device receives an incoming call signal from the basestation during the standby state, it responds to this incoming callsignal by transmitting an incoming call response signal to the basestation.

4) The mobile device receives a communication channel designation signaltransmitted by the base station in response to this incoming callresponse signal, and switches to a communication channel designated bythe communication channel designation signal.

Conventional communication systems using mobile devices of this kind areconstituted in such a manner that an incoming call signal is transmittedfrom a base station to a mobile device, and if, for some reason orother, the base station cannot receive the incoming call response signaltransmitted by the mobile device in response to this incoming callsignal, then the incoming call signal is retransmitted from the basestation to the mobile device.

The time interval from the base station transmitting a first incomingcall signal until it retransmits the signal, in other words, until ittransmits a second incoming call signal because an incoming callresponse signal from the mobile device cannot be received, is set toapproximately 6 seconds, for example.

This interval is determined by taking into account the tolerable waitingtime for the party originating the call and the time required for themobile device to transmit an incoming call response signal afterreceiving an incoming call signal, and the like. If this time intervalis too short, it will not allow sufficient time for dispatch of theincoming call response signal by the mobile device, while if it is toolong, the waiting time for the calling party will become long, which isundesirable.

The mobile device is constituted such that if it has transmitted anincoming call response signal to the base station, but does not receivea communication channel designation signal from the base station withina prescribed period of time, then the mobile device regards thetransmission of the incoming call response signal as having failed, andit carries out a further P-CH scan, whereby it scans the controlchannels again and selects the control channel having the strongestelectric field as the control channel for transmitting and receivingcontrol signals to and from the base station.

The prescribed time period by which it is judged that no communicationchannel designation signal has been received from the base station ifthe prescribed time period has passed after the mobile device hastransmitted an incoming call response signal. This prescribed timeperiod used here is set, for example, to approximately 5 seconds.

This time period from transmission of an incoming call response signalby the mobile device until it is judged that the transmission of theincoming call response signal has failed from the fact that nocommunication channel designation signal has been received, isdetermined on the basis of the time period required by the base stationto transmit a communication channel designation signal after it hasreceived an incoming call response signal. If this time period is tooshort, it will not allow sufficient time for transmission of thecommunication channel designation signal by the base station, while ifit is too long, the device will wait needlessly for a communicationchannel designation signal which cannot be received. Especially, in asituation where the mobile device is waiting to receive thiscommunication channel designation signal using a control channel whichis being shared with another mobile device, the aforementioned timeperiod cannot be made too long from the viewpoint of efficient use ofthe radio channels.

Therefore, at the time that the second incoming call signal transmittedby the base station reaches the mobile device, the mobile device mayhave transferred to carrying out of a P-CH scan, which scans controlchannels and selects the control channel having the greatest fieldstrength as a control channel for transmitting and receiving controlsignal to and from the base station, because it considered thetransmission of the incoming call response signal to have failed. Ifthis transferring to P-CH scan takes place, a problem may arise in thatthe mobile device will not be able to receive the second incoming callsignal transmitted by the base station.

FIG. 6 gives an illustration, in the form of a sequence chart, oftransmission and reception of control signals between a base station anda mobile device in a case where the aforementioned problem occurs.

When the power supply is turned on (Power Supply ON), the mobile devicescans the control channels and selects the control channel having thegreatest field strength as a control channel to use for transmitting andreceiving control signal with a base station (P-CH Scan).

Thereupon, when the mobile device has received control signal from thebase station by means of the control channel selected as describedabove, it assumes a standby state where it awaits a calling operation bythe mobile device or an incoming call signal from the base station.

If the mobile device receives a (first) incoming call signal from thebase station in this standby state, it assumes a connection controlstate where a communication channel is established between the mobiledevice and the base station.

In this connection control operation, firstly, an incoming call responsesignal is transmitted by the mobile device to the base station.

However, if the base station cannot normally receive the incoming callresponse signal, then the base station transmits a further (second)incoming call signal to the mobile device, approximately 6 seconds aftersending the (first) incoming call signal.

On the other hand, if the mobile device has transmitted an incoming callresponse signal, but has not received a communication channeldesignation signal from the base station within approximately 5 seconds,then it regards the transmission of the incoming call response signal tohave failed, and carries out a P-CH scan once again by scanning thecontrol channels and selecting the control channel having the greatestfield strength as a control channel for transmitting and receivingcontrol signal with the base station.

In the case illustrated in FIG. 6, since the incoming call responsesignal from the mobile device has not been received normally at the basestation, the mobile device transfers to a P-CH scan approximately 5seconds after sending the incoming call response signal, and the secondincoming call signal from the base station reaches the mobile devicewhile it is engaged in the P-CH scan. In this case, the mobile device isnot able to receive the (second) incoming call signal from the basestation, and therefore cannot respond to the (second) incoming callsignal.

Consequently, the mobile device will not be able to respond to theincoming call in spite of the fact that the base station has transmitteda (second) incoming call signal.

In this way, in the conventional mobile device, in cases where the basestation transmits a first incoming call signal to the mobile device, andthe base station cannot receive an incoming call response signal sent bythe mobile device in response to the incoming call signal for a reasonof any kind, and the base station therefore transmits a second incomingcall signal to the mobile device, a problem may arise in that, at thepoint in time that this second incoming call signal reaches the mobiledevice, the mobile device may have transferred to a P-CH scan, namely, aP-CH scan whereby, having considered the transmission of the incomingcall response signal to have failed, the mobile device scans the controlchannels once again and selects the control channel having the greatestfield strength as a control channel for transmitting and receivingcontrol signal with the base station. Consequently the mobile devicewill not be able to receive the second incoming call signal transmittedby the base station.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide anincoming call control method and device for a mobile communicationdevice, which are improved in such a manner that the mobilecommunication device can respond to an incoming call swiftly, even incases where there has been a failure in a response to an incoming callsignal from the base station.

In order to achieve the aforementioned object, an incoming call controlmethod is provided for a mobile communication device which selects acontrol channel by scanning control channels for transmitting andreceiving control signals to and from a base station, assumes in astandby state awaiting an incoming call signal which will be transmittedfrom the base station using the control channel thus selected, and, whenan incoming call signal is received from the base station in the standbystate, establishes a communication channel with the base station bymaking incoming call response to the incoming call signal, where in themobile communication device returns to the standby state if the incomingcall response to the incoming call signal from the base station hasfailed.

In one respect of the invention, when an incoming call signal isreceived from the base station in the standby state, the mobilecommunication device selects a new control channel by rescanning thecontrol channels, and makes incoming call response to the incoming callsignal transmitted by the base station by using the control channel thusselected.

In another aspect of the invention, if no incoming call signal has beenreceived from the base station even after a prescribed period of timehas elapsed in the standby state, the mobile communication deviceselects a new control channel by rescanning the control channels, andassumes a standby state awaiting an incoming call signal which will betransmitted from the base station using the control channel thusselected.

According to an aspect of the invention, is an incoming call controldevice is provided for a mobile communication device which selects acontrol channel by scanning control channels for transmitting andreceiving control signals to and from a base station, assumes a standbystate awaiting an incoming call signal which will be transmitted fromthe base station using the control channel thus selected, and, when anincoming call signal is received from the base station in the standbystate, makes incoming call response to the incoming call signal, therebyto establish a communication channel with the base station on the basisof a communication channel designation signal transmitted from the basestation, wherein the incoming call control device comprises incomingcall responding means for transmitting an incoming call response signalto the base station in response to receiving an incoming call signalfrom the base station; incoming call response failure detecting meansfor detecting that incoming call response has failed if no communicationchannel designation signal is received from the base station despite thefact that an incoming call response signal has been transmitted to thebase station by the incoming call responding means; and control meansfor returning the mobile communication device to the standby statewithout carrying out scanning for a new control channel when it isdetected by the incoming call response failure detecting means thatincoming call response has failed.

In another aspect of the invention, the incoming call responding meansselects a new control channel by rescanning the control channels andtransmits an incoming call response signal to the base station using thecontrol channel thus selected when an incoming call signal is receivedfrom the base station in the standby state.

In still another aspect of the invention, the control means selects anew control channel by rescanning the control channels and sets themobile communication device to a standby state awaiting an incoming callsignal transmitted by the base station using the control channel thusselected if no incoming call signal is received from the base stationeven after a prescribed period of time has elapsed in the standby state.

According to another aspect of the invention, is a mobile communicationdevice which is provided selects a control channel by scanning controlchannels for transmitting and receiving control signals to and from abase station, assumes a standby state awaiting an incoming call signalwhich will be transmitted from the base station using the controlchannel thus selected, and, when an incoming call signal is receivedfrom the base station in the. standby state, makes incoming callresponse to the incoming call signal, thereby to establish acommunication channel with the base station on the basis of acommunication channel designation signal transmitted from the basestation, characterized in that the mobile communication device comprisesincoming call responding means for transmitting an incoming callresponse signal to the base station in response to receiving an incomingcall signal from the base station; incoming call response failuredetecting means for detecting that incoming call response has failed ifno communication channel designation signal is received from the basestation despite the fact that an incoming call response signal has beentransmitted to the base station by the incoming call responding means;and control means for returning the mobile communication device to thestandby state without carrying out scanning for a new control channelwhen it is detected by the incoming call response failure detectingmeans that incoming call response has failed.

In another aspect of the invention, the incoming call responding meansselects a new control channel by rescanning the control channels andtransmits an incoming call response signal to the base station using thecontrol channel thus selected when an incoming call signal is receivedfrom the base station in the standby state.

According to another aspect of the invention, the control means selectsa new control channel by rescanning the control channels and sets themobile communication device to a standby state awaiting an incoming callsignal transmitted by the base station using the control channel thusselected if no incoming call signal is received from the base stationeven after a prescribed period of time has elapsed in the standby state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a general configuration of a mobiledevice constituted by applying the incoming call control method anddevice for a mobile communication device according to the presentinvention;

FIG. 2 is a diagram illustrating a state in which radio communication isconducted between the mobile device shown in FIG. 1 and a base station;

FIG. 3 is a flow chart illustrating the operation of a controllersection of the mobile device shown in FIG. 1;

FIG. 4 is a flow chart illustrating a detail of the incoming callresponse processing shown in FIG. 3;

FIG. 5 is a sequence chart illustrating transmission and reception ofcontrol signals between a base station and a mobile device in a casewhere the base station has failed to receive an incoming call responsesignal from the mobile device illustrated in FIG. 1 and a secondincoming call signal is transmitted from the base station to the mobiledevice; and

FIG. 6 is a sequence chart illustrating conventional transmission andreception of control signals between a base station and a mobile devicein a case where the base station has failed to receive an incoming callresponse signal from a mobile device and a second incoming call signalis transmitted from the base station to the mobile device.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the incoming call control method and device for a mobilecommunication device according to the present invention are describedbelow in detail.

FIG. 1 is a block diagram showing the general configuration of a mobiledevice constituted by applying the incoming call control method anddevice for a mobile communication device according to this invention.

In FIG. 1, the mobile device 100 conducts communication with a basestation 200 by establishing a radio channel as illustrated in FIG. 2,and it comprises an antenna 10 for transmitting and receiving radiosignals with a base station 200 as illustrated in FIG. 2; a duplexer 11for outputting a radio signal received via the antenna 10 to a mixer 12and also supplying output from an amplifier 20 to the antenna 10; amixer 12 for mixing a frequency signal corresponding to a receptionchannel output by a synthesizer with the radio signal input from theduplexer 11 and converting them to a base band signal; a demodulatorsection 13 for demodulator the output from the mixer 12; an audiosection 14 for converting the reception signal demodulated by thedemodulator section 13 to a sound signal and outputting it to a speaker15 while also converting a sound signal input via a microphone 16 to atransmission signal and outputting it to a modulator section 17; aspeaker 15 forming a telephone receiver; a microphone 16 forming atelephone transmitter; a modulator section 17 for modulating thetransmission signal output from the audio section 14; a mixer 19 formixing the output of the modulator section 17 and a frequency signalcorresponding to a transmission channel output by the synthesizer 18 andconverting them to a radio signal; an amplifier 20 for amplifying theoutput of the mixer 19; a controller section 21 constituted by a CPU orthe like, for controlling the demodulator section 13, audio section 14,modulator section 17, synthesizer 18 and the like; a display section 22constituted by an LCD or the like and connected to the controllersection 21, for displaying data of various kinds; an operation section23 connected to the controller section 21, for carrying out diallinginput and the like; a random access memory (RAM) 24 connected to thecontroller section 21, which serves as a work area for the controllersection 21; a read-only memory (ROM) 25 connected to the controllersection 21, for storing control programs for the controller section 21and the like; and a sounder 26 connected to the controller section 21,for generating a ringing tone.

When the power supply to this mobile device 100 is turned on by means ofa power supply switch, which is not shown in the drawings, firstly, thecontroller section 21 controls the synthesizer 18 and it conducts a P-CHscan by scanning control channels connected to the base station 200shown in FIG. 2 and, for example, selecting and acquiring the controlchannel having the greatest field strength.

The mobile device 100 receives control data from the base station 200 bymeans of the control channel acquired by the P-CH scan, and it isswitched to a standby state.

When the mobile device 100 has been switched to a standby state, if itreceives an incoming call signal from the base station 200, thisincoming call signal is input to the controller section via the antenna10, duplexer 11, mixer 12 and demodulator section 13.

When the controller section detects reception of an incoming call signalfrom the base station 200, it creates an incoming call response signaland transmits this incoming call response signal to the base station 200via the demodulator section 17, mixer 19, amplifier 20, duplexer 11, andantenna 10.

Upon receiving an incoming call response signal from the mobile device100, the base station 200 transmits a communication channel designationsignal designating the communication channel to be used for the call tothe mobile device 100.

Upon receiving this communication channel designation signal from thebase station 200, the mobile device 100 inputs the communication channeldesignation signal to the controller section, via the antenna 10,duplexer 11, mixer 12, and demodulator section 13, the controllersection 21 controls the synthesizer 18 on the basis of the communicationchannel designation signal, and a communication channel is establishedbetween the mobile device 100 and the base station 200.

Thereupon, the mobile device 100 receives a ringing signal transmittedby the base station 200, and this ringing signal is input to thecontroller section via the antenna 10, duplexer 11, mixer 12, anddemodulator section 13, whereupon the controller section 21 responds todetection of this ringing signal by generating a ringing tone from thesounder 26.

Thereupon, when an off-hook operation is performed by means of theoperation section 23 in response to this ringing tone, an off-hooksignal is transmitted to the base station 200 via the controller section21, modulator section 17, mixer 19, amplifier 20, duplexer 11, andantenna 10, thereby establishing a communication state for conductingcommunication between the mobile device 100 and another party via thebase station 200.

In this communication state, a radio signal received from the basestation 200 is supplied via the antenna 10, duplexer 11, mixer 12,demodulator section 13 and audio section 14 to the speaker 15, where itis output as sound.

A sound signal input via the microphone 16 is transmitted via the audiosection 14, modulator section 17, mixer 19, amplifier 20, duplexer 11and antenna 10 to the base station 200, in the form of a radio signal.

The foregoing description relates to a case where the mobile device 100receives an incoming call signal from the base station 200, but in caseswhere the mobile device 200 originates a call, firstly, an off-hookoperation is performed by means of the operation section 23 and acommunication channel is then established between the mobile device 100and the base station under the control of the controller section 21,whereupon connection with another party is established via the basestation by means of a dial input relating to the other party made viathe operation section 23, and the mobile device 100 then enters acommunication state with the other party.

The operation after a communication state has been assumed is the sameas in cases where the mobile device 100 receives an incoming call signalfrom the base station 200.

In the communication state, if an off-hook operation is made at theother party connected via the base station or at the operation section23 of the mobile device 100, then the communication channel between thebase station 200 and the mobile device 100 is disconnected and themobile device 100 returns to a standby state.

FIG. 3 illustrates the operation of the controller section 21 of themobile device 100 shown in FIG. 1, in the form of a flow chart.

When the power supply of the mobile device 100 is turned on, firstly,reset processing is carried out for each section of the mobile device(step 101), whereupon all the sections of the mobile device areinitialized and P channel selection processing is carried out byscanning the control channels and selecting the control channel havingthe greatest field strength as the control channel between the mobiledevice 100 and the base station 200 (step 102).

Thereupon, the mobile device 100 enters a standby state where it awaitsa calling operation at the mobile device 100 or an incoming call signalfrom the base station 200 (step 103), while acquiring the controlchannel selected by the aforementioned P channel selection processing.

In this standby state, the passage of a prescribed time period ismonitored by means of a timer, which is omitted from the drawings, andwhen this timer performs a time-out, the procedure returns to step 102,and the aforementioned processing is repeating by carrying outinitialization and P channel selection processing once again.

In this standby state, if an incoming call signal is received from thebase station 200, then incoming call response processing is implementedfor making incoming call response to the base station 200 (step 105).

The details of this incoming call response processing are describedlater with reference to the flow chart shown in FIG. 4.

In the incoming call response processing (step 105), if the incomingcall response to the base station 200 fails, then the procedure returnsto step 103 and the mobile device 100 assumes a standby state. In otherwords, it assumes a standby state where it awaits a calling operation inthe mobile device 100 or an incoming call signal from the base station200, while acquiring the control channel selected by the P channelselection processing in step 102.

In the incoming call response processing (step 105), if an incoming callsignal to the base station 200 succeeds, then the mobile device 100switches to a communication channel as designated by a communicationchannel designation signal transmitted by the base station and it entersa ringing signal standby state where it awaits a ringing signal from thebase station 200 in the communication channel to which it has switched(step 107).

In the ringing signal standby state (step 107), if the mobile device 100receives a ringing signal from the base station 200, then it assumes auser operation standby state where it awaits an off-hook operation bythe user (step 108), and if the user performs an off-hook operation atthis stage, then the mobile device 100 enters a communication state withthe base station 200 (step 109).

In either the ringing signal standby state (step 107), the useroperation standby state (step 108) or the communication state (step109), if a cancel operation is performed, then prescribed cancelingprocessing is implemented (step 110), transmission to the base station200 in the communication channel is halted (step 111), and the sequencereturns to step 102.

Furthermore, in the ringing signal standby state (step 107), the useroperation standby state or a case where reception of a ringing signalhas failed (step 108), or the communication state or a case wherephasing has been detected (step 109), if there is a failure incommunication, then transmission to the base station 200 in thecommunication channel is halted immediately (step 111), and the sequencereturns to step 102.

Moreover, in the standby state (step 103), if a calling request isgenerated by a calling operation made by the user, then prescribedcalling processing is carried out (step 106), and if this callingprocessing is successful, then the mobile device 100 enters acommunication state with the base station 200 (step 109), whereas if itfails, then the sequence returns to step 102.

FIG. 4 illustrates the details of incoming call response processing instep 105 in FIG. 3, in the form of a flow chart.

In the incoming call response processing, firstly, an A channel scan forscanning the control channels between the mobile device 100 and the basestation 200 is carried out (step 401). Here, the reason for carrying outthis A channel scan for scanning the control channels between the mobiledevice 100 and the base station 200 is due to the possibility that themobile device 100 may have moved from its state when the control channelwas selected by the P channel selection processing in step 102 in FIG.3, and hence the radio conditions may have changed.

Next, a synchronization establishing operation is carried out betweenthe mobile device 100 and the base station 200 using the control channelacquired by the A channel scan (step 402), and system data from the basestation 200 is detected (step 403).

In the event of a time-out during the synchronization establishingoperation in step 402, in other words, if a prescribed period of timehas elapsed and synchronization has not been established, or in theevent of a time-out during system data detection in step 403, in otherwords, if a prescribed period of time has elapsed and system data hasnot been detected, then a subsequent A channel (control channel) isdetected (step 405), and when it has been detected, the sequence returnsto step 402 and a synchronization establishing operation is carried outusing the subsequent A channel (control channel) thus detected.

After the system data detection at step 403, if the system data isdetected successfully, then it is investigated whether or not to advanceprocessing to the next step (step 404), and if processing is to beadvanced, then the mobile device 100 transmits an incoming call responsesignal to the base station 200 (step 407), and it then investigateswhether a communication channel designation signal has been receivedfrom the base station 200 (step 408).

Here, if a communication channel designation signal is successfullyreceived from the base station 200, for example, if a communicationchannel designation signal is received correctly from the base station200 within a prescribed time period (approximately 5 seconds) from thetransmission of the incoming call response signal at step 407, then themobile device 100 occupies the communication channel designated by thecommunication channel designation signal thus received (step 409), andit then enters a ringing signal standby state (step 107) as illustratedin FIG. 3.

If, at step 408, the mobile device 100 has failed to receive acommunication channel designation signal from the base station 200, forexample, if it has not been able to receive a communication channeldesignation signal from the base station 200 correctly within aprescribed time period (approximately 5 seconds) after transmitting theincoming call response signal at step 407, then the mobile device 100returns to the standby state (step 103) shown in FIG. 3, and assumes astandby state where it awaits a calling operation at the mobile device100 or an incoming call signal from the base station 200, whileacquiring the control channel selected by the P channel selectionprocessing in step 102 in FIG. 3.

If, at step 404, it is determined not to advance processing, or if ithas not been possible to detect a subsequent A channel (control channel)at step 405 (Not Detected), then the sequence returns to step 102 inFIG. 3 and initialization processing and P channel selection processingare carried out.

In this way, by means of this embodiment, in cases where there has beena failure in incoming call response processing with respect to anincoming call signal from the base station 200, specifically, where themobile device 100 has received an incoming call signal from the basestation 200 but has not received a communication channel designationsignal from the base station 200 correctly within a prescribed timeperiod (approximately 5 seconds), then the mobile device 100 returns tothe standby state shown in FIG. 3 (step 103), and it assumes a standbystate where it awaits a calling operation at the mobile device 100 or anincoming call signal from the base station 200, while acquiring thecontrol channel selected by the P channel selection processing in step102 in FIG. 3.

By means of this configuration, in cases where the base station fails toreceive an incoming call response signal from the mobile device andtransmits a second incoming call signal to the mobile device, the mobiledevice can be controlled such that it assumes a state where it canreceive this second incoming call signal, thereby resolving the problemsassociated with conventional devices, namely, situations where themobile device is not able to receive the second incoming call signal andhence cannot respond thereto.

FIG. 5 is a sequence chart illustrating transmission and reception ofcontrol signals between a base station 200 and a mobile device 100 in acase where the base station 200 has failed to receive an incoming callresponse signal from the mobile device 100 and has transmitted a secondincoming call signal to the mobile device 100, in the presentembodiment.

In other words, when the power supply is turned on in the mobile device100 (power supply ON), firstly, it scans the control channels, andselects the control channel having the greatest field strength as acontrol channel for transmitting and receiving control signals with thebase station 200 (P-CH scan).

Upon receiving control data from the base station 100 by means of theselected control channel, the mobile device 100 then assumes a standbystate where it awaits a calling operation at the mobile device 100 or anincoming call signal from the base station 200.

When the mobile device 100 receives a (first) incoming call signal fromthe base station in this standby state, then it enters a connectioncontrol state for establishing a communication channel between themobile device and the base station.

In this connection control process, firstly, an A-CH scan is carriedout, and a new control channel is acquired, whereupon the mobile devicesends an incoming call response signal to the base station using thisnew control channel.

Thereupon, if the base station does not receive the incoming callresponse signal correctly, then this is regarded as an incoming callresponse signal reception failure at the base station, and the basestation then transmits a further (second) incoming call signal to themobile device approximately 6 seconds after sending the aforementioned(first) incoming call signal.

If the mobile device, on the other hand, has transmitted an incomingcall response signal, but has not received a communication channeldesignation signal from the base station within approximately 5 seconds,then it regards the incoming call response signal transmission as havingfailed, and it returns to the standby state shown in FIG. 3 (step 103),and assumes a standby state where it awaits a calling operation at themobile device 100 or an incoming call signal from the base station 200,while acquiring the control channel selected by the P channel selectionprocessing at step 102 in FIG. 3.

Since the mobile device 100 is able to receive the (second) incomingcall signal from the base station 200 while in this standby state, it ispossible for the mobile device to receive the second incoming callsignal from the base station 200, whereby it is possible for the mobiledevice to transfer swiftly to a connection control state in response tothe (second) incoming call signal from the base station 200 thusreceived.

In the aforementioned embodiment, the reason why the mobile device isconstituted in such a manner that it returns to the standby state (step103) shown in FIG. 3, if it has transmitted an incoming call responsesignal but there has been a failure in the transmission process of thisincoming call response signal, is due to the fact that there is a highprobability that it will be able to receive a (second) incoming callsignal in this standby state, since it was at least able to receive the(first) incoming call signal from the base station 200 in the previouslymentioned standby state.

This invention provides an incoming call control method and device for amobile communication device, which are improved in such a manner that aswift response to an incoming call is possible even in cases where therehas been a failure in a response to an incoming call signal from a basestation. By means of this invention, since a configuration is adoptedwhereby even if a response to an incoming call signal from a basestation has failed, the mobile device will return to a standby stateprior to reception of an incoming call signal from the base station,without carrying out a scan for a new control channel, it is thereforepossible for the mobile device to respond to an incoming call andtransfer to connection control swiftly in cases where the base stationtransmits a second incoming call signal to the mobile device because ithas failed to receive an incoming call response signal from the mobiledevice, and therefore an advantage is obtained in that the mobile deviceis able to make connections to a base station in a reliable manner.

What is claimed:
 1. An incoming call control method for a mobilecommunication device comprising the steps of: (a) selecting a controlchannel by scanning a plurality of control channels; (b) setting themobile communication device to a standby state awaiting an incoming callsignal to be transmitted from a base station over the selected controlchannel; (c) performing an incoming call response procedure fortransmitting an incoming response signal to respond to an incoming callsignal if the incoming call signal is received from the base station inthe standby state; (d) establishing a communication channel with thebase station so that the mobile communication device is in acommunicating state if the incoming call response procedure to theincoming call signal from the base station succeeds; and (e) setting themobile communication device to the standby state awaiting an incomingcall signal to be transmitted from the base station over the selectedcontrol channel without scanning the channels if the incoming callresponse procedure to the incoming call signal from the base stationfails.
 2. The incoming call control method for a mobile communicationdevice according to claim 1, wherein the incoming call responseprocedure comprises the steps of: selecting a control channel byscanning the plurality of control channels; performing a synchronizationprocedure to establish synchronization with the selected controlchannel; transmitting an incoming call response signal to the basestation over the selected control channel with which synchronization isestablished in the synchronization procedure; performing a communicationchannel designation signal receiving procedure to receive acommunication channel designation signal transmitted from the basestation in response to the transmission of the incoming call responsesignal; and capturing a communication channel designated based on thecommunication channel designation signal if the communication channeldesignation signal is received in the communication channel designationsignal receiving procedure.
 3. The incoming call control method for amobile communication device according to claim 1, wherein if no incomingcall signal is received from the base station after a prescribed periodof time has elapsed from a start of the standby state in the step (e),the mobile communication device selects a new control channel byrescanning the control channels and sets the mobile communication deviceto a standby state awaiting an incoming call signal to be transmittedfrom the base station over the selected new control channel.
 4. Anincoming call control device for a mobile communication device whichselects a control channel by scanning a plurality of control channels,sets the mobile communication device to a standby state awaiting anincoming call signal to be transmitted from a base station over theselected control channel, and if an incoming call signal is receivedfrom the base station in the standby state, makes incoming call responseto the received incoming call signal, thereby establishing acommunication channel with the base station on the basis of acommunication channel designation signal transmitted from the basestation, comprising: incoming call responding means for transmitting anincoming call response signal to the base station in response toreceiving an incoming call signal from the base station; incoming callresponse failure detecting means for detecting that incoming callresponse fails if no communication channel designation signal isreceived from the base station after an incoming call response signal istransmitted to the base station by the incoming call responding means;and control means for setting the mobile communication device to apredetermined state corresponding to the standby state without scanningthe control channels if the incoming call response failure detectingmeans detects that the incoming call response fails.
 5. The incomingcall control device for a mobile communication device according to claim4, wherein if an incoming call signal is received from the base stationin the predetermined state, the incoming call responding means selects anew control channel by rescanning the control channels and transmits anincoming call response signal to the base station over the selected newcontrol channel.
 6. The incoming call control device for a mobilecommunication device according to claim 4, wherein if no incoming callsignal is received from the base station after a prescribed period oftime has elapsed from a start of a predetermined state, the controlmeans selects a new control channel by rescanning the control channelsand sets the mobile communication device to a standby state awaiting anincoming call signal to be transmitted by the base station over theselected new control channel.
 7. A mobile communication device whichselects a control channel by scanning a plurality of control channels,sets the mobile communication device to a standby state awaiting anincoming call signal to be transmitted from a base station over theselected control channel, and if an incoming call signal is receivedfrom the base station in the standby state, makes incoming call responseto the received incoming call signal, thereby establishing acommunication channel with the base station on the basis of acommunication channel designation signal transmitted from the basestation, comprising: incoming call responding means for transmitting anincoming call response signal to the base station in response toreceiving an incoming call signal from the base station; incoming callresponse failure detecting means for detecting that incoming callresponse fails if no communication channel designation signal isreceived from the base station after an incoming call response signal istransmitted to the base station by the incoming call responding means;and control means for setting the mobile communication device to apredetermined state corresponding to the standby state without scanningthe control channels if the incoming call response failure detectingmeans detects that the incoming call response fails.
 8. The mobilecommunication device according to claim 7, wherein if an incoming callsignal is received from the base station in the predetermined state, theincoming call responding means selects a new control channel byrescanning the control channels and transmits an incoming call responsesignal to the base station over the selected new control channel.
 9. Themobile communication device according to claim 7, wherein if no incomingcall signal is received from the base station after a prescribed periodof time has elapsed from a start of the predetermined state, the controlmeans selects a new control channel by rescanning the control channelsand sets the mobile communication device to a standby state awaiting anincoming call signal to be transmitted by the base station over theselected new control channel.
 10. A mobile communication devicecomprising: selecting means for selecting a control channel by scanninga plurality of control channels; first setting means for setting themobile communication device to a standby state awaiting an incoming callsignal to be transmitted from a base station over the selected controlchannel; receiving means for receiving the incoming call signal;transmitting means for transmitting an incoming call response signal inresponse to the received incoming call signal; detecting means fordetecting whether a communication channel designation signal is receivedfrom the base station for a predetermined time period after the incomingcall response signal is transmitted; and second setting means forsetting the mobile communication device to a predetermined statecorresponding to the standby state awaiting an incoming call signal tobe transmitted from the base station over the selected control channelif the communication designation signal is not received for thepredetermined time period.
 11. The mobile communication device accordingto claim 10, wherein if the incoming call signal is received from thebase station in the predetermined state, the selecting means selects anew control channel by scanning the control channels and transmits theincoming call response signal to the base station over the selected newcontrol channel.
 12. The mobile communication device according to claim10, wherein if the incoming call signal is not received from the basestation for a predetermined time period from a start of thepredetermined state, the selecting means selects a new control channelby scanning the control channels and sets the mobile communicationdevice to a standby state awaiting an incoming call signal to betransmitted over the selected new control channel.